Seafood sampling sites along the Northern Gulf of Mexico were identified based on an East-West geographical distribution, and public, shoreline community access to active fishing, with varying degrees of direct oil spill impact (see map on Background page). We have engaged with community and recreational fishers to contribute seafood samples for contaminant analyses. Coastal citizens from different Gulf regions within the project also contribute important seafood consumption data using an on-site survey tool administered through a brief personal interview.
Seafood sample collection:
Fresh seafood catches collected and analyzed for oil spill-related contaminants includes finfish, blue crab, oyster, and white and brown shrimp. These seafood types represent the overwhelming majority of seafood that is locally caught, and has local and regional economic value.
Fish samples are taken with skin on, but without scales. After scales are removed (left picture) the center portion of the left filet is cut into four 5-gram samples that include complete dorsal-to-ventral (top to bottom) sections (right image). Edible portions of crab, shrimp and oyster are also processed for chemical analyses.
Engagement with regional communities as been an essential component to the sucess of this project. Citizen input has been a valued asset in the project design and implementation, and will be fundamental in communicating project outcomes so that information can be understood and, most importantly, is meaningful.
Seafood samples are sometimes processed directly in the field, such as at this fishing rodeo in Pensacola, FL. Undertaking seafood collections and tissue processing at fishing tournaments and community events supports opening easy dialog with the public, and an opportunity to answer questions in an informal atmosphere. Above, 10-year-old William Lindholm (far right) from Pace, Florida, talks with postdoctoral research associate Joe Bisessi:
William: So, are you a student?
Joe: “Why yes I am.”
William (after a moment to think): They make you work during the summer?!
Joe: Yes, we work all year-round.
William: Wow. That’s rough. Well, at least you get to come to Pensacola Beach!
Seafood sample Analysis:
In the field, or in a field laboratory, or back at the Aquatic Pathobiology Laboratories in Gainesville, samples for organic analyses are wrapped in clean aluminum foil (left), and samples for metal analysis are placed directly in poly bags (right). Sealed, labeled bags are frozen on dry ice and maintained under chain of custody in a freezer until further processing for analyses.
Frozen samples are homogenized, extracted and partitioned with an organic solvent and salt solution, and cleaned using dispersive Solid Phase Extraction (dSPE) prior to quantitative analysis using mass spectroscopy on a gas chromatograph (right). PAH parent compounds and their alkyl homologs are discerned, based on a 6-points standard curve and use of internal standards.
A combination of analytical chemistry data and seafood consumption data collected from this study will be used to provide risk assessment for the different regions sampled. The seafood survey tool provides information about the types of Gulf seafood that folks eat, how often they eat it, and how much they eat. For example, a validated plated portion size guide (below) helps survey participants best estimate how much fish they eat, when they have fish for a meal. Similar portion images for shrimp and crab are included in the guide.
With the analytical chemistry data and the seafood consumption information, we can discern cumulative level of concern (LOC) for the various carcinogenic PAHs that could be identified in seafood based on benzo[a]pyrene equivelent concentrations (BapE):
LOC = (RL×BW×AT×CF)/(CSF×CR×ED)
RL = risk level (1E-05)
BW = body weight (kg)
AT = averaging time (78 years)
CF = conversion factor (1000 μg/mg)
CSF = cancer slope factor (7.3 mg/kg-day)-1
CR = consumption rate (g/day)
ED = assumed exposure duration (5 years)